1. Field of the Invention.
The present invention relates to the oil field service industry, and more particularly but not by way of limitaion, to downhole equipment and the recovery of same.
2. Discussion of Prior Art.
The patent issued to Larson, U.S. Pat. No. 2,272,529, on February 10, 1942 taught a fishing tool for the recovery of separated sucker rods. Larson's fishing tool used a barrel body which had an eccentric sleeve that was positionable via selective rotation of the barrel to grip the downhole sucker rod portion that has separated. Once gripped, the fishing tool was brought to the surface, pulling the separated sucker rod with it.
The patent issued to Taylor, U.S. Pat. No. 4,185,865, on January 29, 1978, taught a fishing tool, also sometimes referred to as an overshot, which was operable on a wireline. A retractable set of collet fingers mounted in an overshot body is engageable with a fish (a downhole member that is to be retrieved), and repeated bumping against the fish extending into the collet fingers results in the opening or closing of the collet fingers via cam actuated internal rotation of the collet fingers, and the fish pulls the collet fingers into gripping engagement as it pulls the closed collet fingers through the tapered opening of the overshot body.
While the Larson and Taylor patents taught improvements in an area occupied with numerous prior art fishing devices, certain deficiencies remain, notably the ability to exercise positive control at the surface over subsurface, downhole fishing assemblies.